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Drugs that activate the serotonergic 5-HT2A receptor (e.g. LSD, psilocybin, mescaline) are notorious for causing psychedelic experiences and I would like to know the neurochemical mechanism behind this.

"Speculatively, if deep-layer pyramidal cells were to become hyperexcitable during the psychedelic state, information processing would be biased in the direction of inference—such that implicit models of the
world become spontaneously manifest—intruding into consciousness without prior invitation from sensory data. This could explain many of the subjective effects of psychedelics."